[postgis-users] Problem with ST_intersects

Tue Jun 21 17:58:39 PDT 2011

Upgraded on CentOS to

  POSTGIS="1.5.3SVN" GEOS="3.1.1-CAPI-1.6.0" PROJ="Rel. 4.7.1, 23 September 2009" LIBXML="2.6.26" USE_STATS

And the problem still occurs:

  plm25new=>  select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b where a.id =1954;
    id  | st_intersects
  ------+---------------
   1954 | t
  (1 row)

  plm25new=>  select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b where a.id = 2034 or a.id =1954;
    id  | st_intersects
  ------+---------------
   2034 | t
   1954 | f
  (2 rows)

The problem does not occur with ST_Relate:

plm25new=>  select  a.id, ST_relate(a.the_geom, b.the_geom) from apoly as a, aright as b where a.id = 2034 or a.id =1954;
    id  | st_relate
  ------+-----------
   2034 | 0FFFFF212
   1954 | 0FFFFF212
  (2 rows)

Also it does not seem to occur if I make the point into a tiny polygon:

plm25new=>  select  a.id, ST_intersects(st_buffer(a.the_geom,10e-8), b.the_geom) from apoly as a, aright as b
  where a.id = 2034 or a.id =1954;
  id  | st_intersects
------+---------------
 2034 | t
 1954 | t
(2 rows)

In fact I have just noticed I can cause all sorts of problems by using different where clauses - could it be some sort of caching problem?

  plm25new=>  select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b where id=2034  order by a.id;
   id  | st_intersects
  ------+---------------
   2034 | t
  (1 row)

  plm25new=>  select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b where id=2033  order by a.id;
    id  | st_intersects
  ------+---------------
   2033 | t
  (1 row)

  plm25new=>  select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b where id=1954  order by a.id;
    id  | st_intersects
  ------+---------------
   1954 | t
  (1 row)

  plm25new=>  select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b where id=2033 or id=1954 order by a.id;
    id  | st_intersects
  ------+---------------
  1954 | t
  2033 | f
  (2 rows)

  plm25new=>  select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b where id=2034 or id=1954 order by a.id;
    id  | st_intersects
  ------+---------------
   1954 | f
   2034 | t
  (2 rows)

  plm25new=>  select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b order by a.id;
    id  | st_intersects
  ------+---------------
   1954 | f
   2033 | f
   2034 | t
  (3 rows)

----
James Sewell
Solutions Architect
Ardec International
Office: (03) 86803200
Mobile: 0414 688 892

________________________________________
From: postgis-users-bounces at postgis.refractions.net [postgis-users-bounces at postgis.refractions.net] On Behalf Of James Sewell [James.Sewell at lisasoft.com]
Sent: Wednesday, 22 June 2011 10:10 AM
To: PostGIS Users Discussion; postgis-dev at postgis.refractions.net
Subject: Re: [postgis-users] Problem with ST_intersects

Aha,

http://trac.osgeo.org/postgis/ticket/845

I will upgrade to 1.5.3 and retest!

----
James Sewell
Solutions Architect
Ardec International
Office: (03) 86803200
Mobile: 0414 688 892

________________________________________
From: postgis-users-bounces at postgis.refractions.net [postgis-users-bounces at postgis.refractions.net] On Behalf Of James Sewell [James.Sewell at lisasoft.com]
Sent: Tuesday, 21 June 2011 1:58 PM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] Problem with ST_intersects

Sorry, I forgot to say I have encountered the problem with the following versions / OSes

 CentOS: POSTGIS="1.5.2" GEOS="3.1.1-CAPI-1.6.0" PROJ="Rel. 4.7.1, 23 September 2009 " LIBXML="2.6.26" USE_STATS

 Solaris: POSTGIS="1.5.2" GEOS="3.1.1-CAPI-1.6.0" PROJ="Rel. 4.7.1, 23 September 2009" LIBXML="2.6.31" USE_STATS

----
James Sewell
Developer
LISAsoft

________________________________________
From: postgis-users-bounces at postgis.refractions.net [postgis-users-bounces at postgis.refractions.net] On Behalf Of James Sewell [James.Sewell at lisasoft.com]
Sent: Tuesday, 21 June 2011 1:50 PM
To: postgis-users at postgis.refractions.net
Subject: [postgis-users] Problem with ST_intersects

Hello All,

I think I have found a bug. For the data attached the following commands yield interesting results, with the output of ST_intersects seemingly changed by the where clause.

  plm25=> select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b where a.id = 1954 or a.id =2034 order by id;
    id  | st_intersects
  ------+---------------
   1954 | f
   2034 | t
  (2 rows)

  plm25=> select  a.id, ST_intersects(a.the_geom, b.the_geom) from apoly as a, aright as b  where a.id = 1954 or a.id =2033 order by id;
    id  | st_intersects
  ------+---------------
   1954 | t
   2033 | t
  (2 rows)

Anyone have any ideas why this might be so?

----
James Sewell
Solutions Architect
Ardec International
Office: (03) 86803200
Mobile: 0414 688 892

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